1xe2x80x94Field of the Invention
The present invention relates to a modulatable energy absorption device for automobile vehicle steering columns which uses pyrotechnic charges.
The device in accordance with the invention applies in particular to a steering column whose depth and/or inclination is adjustable, whose steering shaft is mounted in a body-tube, which is supported by and locked to the vehicle in the required position. The invention can also apply to a non-adjustable steering column.
2xe2x80x94Description of the Prior Art
The increasing improvement of the safety of steering columns requires manufacturers to control all the parameters of the energy absorbing systems. Thus, in the case of the method of absorbing energy by uncoiling a wire, which is increasingly used on steering columns, consideration has been given to modulating the absorption of energy as a function of characteristics of the driver, such as in particular their weight and whether or not their seat belt is fastened and as a function of the speed of the vehicle.
An object of the present invention is to propose a modulatable energy absorbing device which uses coiled wires of simple shapes which are easy to make but can absorb exactly the amount of energy to be dissipated as a function of characteristics of the driver and the vehicle and which mounts easily within the overall dimensions of existing steering columns.
One embodiment of the invention relates to a modulatable device for absorbing energy from an automobile vehicle steering column, which includes a steering shaft rotatably mounted in a body-tube connected to a support assembly fixed to the vehicle, characterized in that said modulatable energy absorbing system includes:
a fixed support fastened to the vehicle and a mobile support which is connected to and locked to the fixed support with a particular clamping force such that said locking ceases in the event of an impact; and
at least two coils of a metal member with a particular section, which are connected to the fixed support and to the mobile support by a retaining pin and by an attachment pin, respectively;
the coils being mounted on one or more rollers disposed on the retaining pin fastened to the fixed support member and each having a rectilinear portion in substantially the same direction as the force to be damped, and a free end which is attached to the corresponding attachment pin disposed at one end of the mobile support, at the same end as the steering rack, i.e. at the opposite end to the steering wheel, and at least one coil having its attachment pin or its retaining pin in the form of a holding rod adapted to be moved along its axis by pyrotechnic displacement means which are actuated by actuator means, so that in the event of an impact the mobile support is connected to the fixed support by a number of coils suitable for the energy to be absorbed.
In the event of an impact, the above arrangement connects the mobile support to the fixed support by means of a required number of coils, determined according to the weight of the driver, whether or not the driver""s seat belt is fastened, and the speed of the vehicle.
Accordingly the mobile support, which is connected to the body-tube and therefore to the steering wheel, pulls on the free end of the coil(s) attached to the corresponding attachment pin so that the coil(s) concerned are uncoiled to absorb the energy to be dissipated.
In different architectures in accordance with the invention, for attaching or for retaining the coils, at least one coil has a movable holding rod that is substantially horizontal or vertical.
In accordance with the invention, three coils are advantageously mounted on a roller disposed around a retaining pin and are attached to movable holding rods having corresponding pyrotechnic actuators which are substantially vertical.
In another embodiment of the invention, three coils are mounted on a roller disposed around a retaining pin, one of them is attached to a fixed holding rod supported by two bearings, and the other two are attached to corresponding movable holding rods supported by two bearings and each having a pyrotechnic actuator.
In another embodiment of the invention, three coils are each mounted on a corresponding roller disposed around a retaining pin, one of them is attached to a fixed holding rod supported by two bearings, and the other two are each attached to corresponding movable holding rods supported by two bearings and each having a pyrotechnic actuator.
In this embodiment of the invention, the coil attached to a fixed holding rod is the central coil.
In accordance with another embodiment of the invention, three coils are each mounted on a corresponding roller disposed around a corresponding substantially vertical retaining pin, the central coil being retained by a fixed holding rod supported by two central bearings, and each lateral coil being retained by a movable holding rod supported by two corresponding lateral bearings, and having a corresponding pyrotechnic actuator, the three coils being attached to a single attachment pin consisting of a fixed holding rod supported by two central bearings and two lateral bearings.
In one type of detailed structure of the invention:
the fixed support includes a base with two substantially vertical lugs between which the mobile support is engaged, each of the lugs having a hole in it through which the retaining pin passes;
the mobile support has two substantially vertical lateral parts and a connecting portion; and
each of the lateral parts has an oblong hole in its upper part through which the retaining pin passes and the oblong hole has a length corresponding to the energy absorption travel.
In this type of structure, the retaining pin is a rod with a sleeve, said sleeve is disposed between the two lateral parts of the mobile support, said rod is held at each of its two ends by a fixing assembly in the corresponding lug of the fixed support and by a sliding assembly of the mobile support; each fixing assembly is locked onto each of the lugs with a particular force.
Each fixing assembly includes a clamping washer disposed between the sleeve and the corresponding lug of the fixed support, said clamping washer including a tube passing through the oblong hole in the corresponding lateral part of the mobile support and a corresponding threaded end of the rod passes through the tube of the clamping washer and the hole through the corresponding lug to receive a clamping nut, which is applied to said lug in order to lock the fixing assembly at a particular value.
Each sliding assembly includes an external washer with a square protuberance and an internal washer with a square hole which receives said square protuberance;
said square protuberance has a hole in it through which the tube of the clamping washer passes;
the external washer is disposed between the corresponding lug of the fixed support and the corresponding lateral part of the support;
the internal washer is disposed between said lateral part and the clamping washer;
the square protuberance passes through and slides in the corresponding oblong hole of the mobile support.
In another embodiment, the rod has one of its two ends threaded and the other end consists of a head applied to the corresponding lug of the fixed support.
In this first type of structure, the attachment pin consists of the central fixed holding rod and the two lateral movable holding rods, each of which has a pyrotechnic actuator, which is disposed on and fixed to the corresponding external bearing face of the mobile support; the lateral mobile holding rods pass through a corresponding hole in each of the lateral parts of the mobile support, and are supported by corresponding bearings which are part of a bracket mounted on and fixed to the connecting portion of the end of the mobile support; the central fixed holding rod is supported by the two bearings; a closure member of the bracket surrounds the end of the mobile support, the bracket and the free ends of the coils, said closure member being assembled to the mobile support and the bracket.
A second type of detailed structure of the invention includes:
a retaining pin consisting of a central fixed holding rod and two lateral movable holding rods, each of which has a pyrotechnic actuator; and
two rollers mounted on a thin tube in which the lateral movable holding rods slide, and a roller mounted on the central fixed holding rod, which is mounted on the thin tube.
In this second type of structure, each of the two lateral movable holding rods has a pyrotechnic actuator disposed on and fixed to the external face of the corresponding lug of the fixed support; the retaining pin has at each end a fixing assembly in the corresponding lug of the fixed support and a sliding assembly of the corresponding lateral part of the mobile support; each fixing assembly is locked to each of the lugs with a particular clamping force; each of the movable lateral holding rods passes through or engages in the corresponding fixing assembly.
Each fixing assembly includes a metal tube which passes through the oblong hole in the corresponding lateral part of the mobile support and which passes through the hole through the corresponding lug; an internal taper is provided at the same end as said lateral part and an external taper is provided at the same end as said lug in order to lock the fixing assembly.
Each sliding assembly includes an external washer with a square half-protuberance and a hole through it, and an internal washer with a square half-protuberance and a hole through it, each half-protuberance nesting in the other washer by means of tenons entering the holes to form a square protuberance; the external washer is disposed between the corresponding lug of the fixed support and the corresponding lateral part of the mobile support; the internal washer is disposed between said lateral part and the internal taper of the metal tube; the square protuberance passes through and slides in the corresponding oblong hole in the lateral part of the mobile support.
Moreover, the tube is supported by four bearings which form part of a bracket mounted on and fixed under the base of the fixed support.
In the second type of structure, the attachment pin includes three semi-circular notches at the edge of the connecting portion which forms part of the end of the mobile support; each notch receiving the free end of one of the aforementioned coils.
The modulatable energy absorbing device in accordance with the invention has the advantage of having a structure that is simple to construct, with guaranteed quality in mass production, as is the case in the automobile industry. Moreover, the device is easy to mount within the overall dimensions of existing steering columns. Finally, the modulatable energy absorbing device matches the energy absorbed exactly to what is required, allowing in particular for the weight of the conductor, whether or not the seat belt is being worn and the speed of the vehicle, all this in combination with the same uncoiling travel.